Known in the art are methods of and means for emptying pipes driven into earth in nontrench laying which are based upon cyclic digging, picking-up and removal of spoil from a pipe by means of scoops, barrels, special conveyors, hydraulic monitors or by hand (see, for example, Lavrov G. E. Modern Methods of Constructing Underground Crossings, GosINTI, 1960; Lavrov G. E., Construction of Underground Pipeline Crossings, VNIIST Glavgaza U.S.S.R., 1961).
The forementioned methods and means of the prior art suffer from the disadvantage that they involve a large amount of auxiliary work before and after the pipe emptying job, high percentage of manual labour, and cumbersome equipment.
Also known in the art as a method of emptying pipes driven into earth in nontrench laying which is based upon spoil digging, picking-up and removal operations performed in cycles as the pipe involved is driven into earth.
The device for carrying this method into effect comprises a working element adapted to dig, pick up and remove spoil and provided with a means for retaining the spoil load during withdrawal thereof and further comprises a mechanism designed for moving the working element and kinematically connected therewith.
The working element of this device operates on the principle of a backshovel and comprises a frame which mounts a scoop with a cutting edge and an apron.
The mechanism for moving the working element is constructed as a winch kinematically connected with the parts of the working element through a system of ropes and guide pulleys (see, for example, the Builder's Handbook on Construction of Urban Gas Supply Systems, Moscow, Stroiizdat, 1976, pages 288-290).
Pulling the ropes moves the scoop up and down so that the scoop cutting edge digs spoil, the apron being filled with the material.
After the apron is filled up, the working element is withdrawn from the pipe by means of the winch, the apron is emptied out, the pipe is driven further into earth and the cycle is repeated.
Inasmuch as the outer surface of the scoop makes contact with the inner surface of the pipe, the working element of the device under consideration is applicable only to one pipe diameter.
The working element constructed as a scoop with a cutting edge and an apron cannot be used for emptying the entire length of a pipe already driven into earth and therefore the pipe has to be driven a short distance after each emptying cycle, which complicates and lengthens the emptying process and, consequently, reduces the rate of work.
Furthermore, the emptying process is lengthened due to slow digging, picking-up and removal of spoil, since inserting the working element into the pipe, moving the scoop to the spoil, digging the spoil, loading, removing the apron with the spoil load from the pipe, and discharging the spoil load from the apron are all separate operations causing waste of time.
The cumbersome construction of the working element and its moving mechanism and the complicated kinematic connection therebetween make it impossible to use said device where maneuverability is required for emptying several pipes in succession.